Optical probe having an inner tube with separable tube sections to house optical elements

ABSTRACT

An optical probe ( 10 ) including one or more optical elements ( 32 ), and an inner tube ( 30 ) to house the optical elements. The inner tube may be made up of at least two cooperating inner tube sections ( 34, 36 ) separable from one another along a longitudinal axis of the inner tube.

This application claims benefit of the 15 Aug. 2013 filing date ofUnited States Provisional Patent Application No. 61/866,206, which isincorporated by reference herein.

FIELD OF THE INVENTION

The invention is generally directed to monitoring of turbine engines,and, more particularly, to an optical probe for optical monitoring ofturbine engines.

BACKGROUND OF THE INVENTION

Notwithstanding of advances which have been made in this technicalfield, there continues to be a need for improved apparatus and/ortechniques useful for monitoring high-temperature regions of interest ina turbine engine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of thedrawings that show:

FIG. 1 is an isometric view of a non-limiting embodiment of an opticalprobe embodying aspects of the present invention, which may be used foroptical monitoring of various components of a combustion engine, e.g., aturbine engine.

FIG. 2 is a generally cross-sectional view of one non-limitingembodiment of an optical probe embodying aspects of the presentinvention.

FIG. 3 is an isometric view of an inner tube of an optical probeembodying aspects of the present invention, where it can be appreciatedthat in one non-limiting embodiment, the inner tube may comprise atleast two inner tube sections separable from one another along alongitudinal axis of the inner tube.

FIG. 4 is an isometric view where the inner tube sections of the innertube are shown attached to one another, and further illustrates alight-redirecting element, (e.g., prism, mirrors) which may be supportedat a distal end of the inner tube by an affixing structure embodyingfurther aspects of the present invention.

FIG. 5 is an isometric view illustrating further details in connectionwith the affixing structure illustrated in FIG. 4.

FIG. 6-8 each illustrates respective flow charts of non-limitingembodiments of methods that may be practiced in connection with opticalprobes disclosed herein for monitoring turbine engines.

FIG. 9 shows respective isometric views of two separate tubingstructures, which may be asymmetrically bifurcated to compensate forloss of material to construct an optical probe embodying aspects of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have innovatively recognized that theserviceability of existing optical probes for monitoring components ofcombustion engines, e.g., turbine engines, may be substantially limitedby the monolithic (e.g., single-piece) construction of structures thatcontain various optical elements which may be utilized by such opticalprobes to convey imaging data to an imaging sensor. In case of breakageof any of such optical components, gaining accessibility to replace orrepair any such components is substantially burdensome, if at allfeasible. The present inventors have further recognized that opticalproperties of certain optical elements (e.g., a prism) of existingoptical probes may be impaired when such elements are attached by way ofepoxies that may involve one or more optically-working surfaces of theprism.

In accordance with one or more embodiments of the present invention,structural arrangements and/or techniques conducive to an improvedoptical probe are described herein. For example, in lieu of asingle-piece construction, in one non-limiting embodiment, such improvedoptical probes may provide an inner tube comprising at least twocorresponding inner tube sections separable from one another along alongitudinal axis of the inner tube. In another non-limiting embodiment,such improved optical probes, may provide an affixing structure notattached to an optically-working surface of a light-redirecting element(e.g., prism, mirrors). In the following detailed description, variousspecific details are set forth in order to provide a thoroughunderstanding of such embodiments. However, those skilled in the artwill understand that embodiments of the present invention may bepracticed without these specific details, that the present invention isnot limited to the depicted embodiments, and that the present inventionmay be practiced in a variety of alternative embodiments. In otherinstances, methods, procedures, and components, which would bewell-understood by one skilled in the art have not been described indetail to avoid unnecessary and burdensome explanation.

Furthermore, various operations may be described as multiple discretesteps performed in a manner that is helpful for understandingembodiments of the present invention. However, the order of descriptionshould not be construed as to imply that these operations need beperformed in the order they are presented, nor that they are even orderdependent unless otherwise so described. Moreover, repeated usage of thephrase “in one embodiment” does not necessarily refer to the sameembodiment, although it may. Lastly, the terms “comprising”,“including”, “having”, and the like, as used in the present application,are intended to be synonymous unless otherwise indicated.

FIG. 1 is an isometric view of a non-limiting embodiment of an opticalprobe 10 embodying aspects of the present invention, which may be usedfor optical monitoring (e.g., inspection) of various components 12(e.g., blades, vanes, etc.) of a combustion engine 14, e.g., a turbineengine. Optical probe 10 may be mounted through a viewing port 15 in aturbine casing 16 and may be partially disposed within a path 17 ofhot-temperature working gases for the engine. Circle 19 is used toconceptualize one non-limiting example of a field of view which may beprovided by optical probe 10.

FIG. 2 is a generally cross-sectional view of one non-limitingembodiment of an optical probe 10 embodying aspects of the presentinvention. Probe 10 may comprise a fitting 20 including a port 21 and aplenum 23 for receiving a controllable supply of a cooling fluid, whichin one non-limiting embodiment may be gaseous nitrogen (GN2). Probe 10may further comprise an intermediate outer tubing 22 connected at aproximate end 24 to fitting 20 and at a distal end 26 to a probe tip 28,which may comprise a viewing window 27 and which may also define anopening for purging cooling fluid (schematically represented by arrow25). Outer tubing 22 and probe tip 28 may be configured to receive intheir respective hollowed interiors an inner tube 30, which may house atleast one optical element (e.g., one or more optical lenses 32, whichmay be arranged as relay optics).

FIG. 2 further illustrates an imaging sensor 33, responsive to imagingdata of one or more components of turbine engine disposed in the fieldof view of the probe and which imaging data may be conveyed to imagingsensor 33 by the relay optics. Imaging sensor 33 in one non-limitingembodiment may be an infrared (IR) camera (e.g., which may operate inthe near-IR spectrum) or other suitable two-dimensional imaging sensingarray. In one non-limiting embodiment, in lieu of optical lenses,optical fibers may be used to convey the imaging data to imaging sensor33.

FIG. 3 is an isometric view of inner tube 30, where it can beappreciated that in one non-limiting embodiment inner tube 30 maycomprise at least two corresponding and cooperating inner tube sections34, 36 separable from one another along a longitudinal axis 38 of innertube 30. FIG. 3 illustrates inner tube sections 34, 36 in a separatedcondition while FIG. 4 illustrates inner tube sections 34, 36 in ajoined condition. That is, inner tube sections 34, 36 are illustrated inFIG. 4 as being attached to one another.

FIG. 3 further illustrates that one of the inner tube sections (e.g.,inner tube section 36) may be filled with a series of optical lenses 40(e.g., relay optics) stacked along the longitudinal axis 38 of innertube 30. In one non-limiting embodiment, at least one optical spacer 42may be interposed between at least a pair of the optical lenses. In onenon-limiting embodiment, inner tube sections 34, 36 of inner tube 30 maydefine a hollowed interior having a varying diameter, as conceptuallyrepresented by the twin-headed arrows labeled D1 and D2, which in turnallows accommodating optical elements having a varying diameter. In onenon-limiting embodiment, inner tube 30 may include at least onealignment tab 44 formed on an outer surface of inner tube 30. Inner tube30 may further include a stop 46 formed on its outer surface. In onenon-limiting embodiment, inner tube 30 may be configured to definerespective annular spaces 29, 31 (FIG. 2) between its outer surface andthe respective inner surfaces of outer tubing 22 and probe tip 28. Theseannular spaces allow externally-supplied cooling fluid to flow betweensuch surfaces and this cooling arrangement is expected to avoid a needfor relatively costly and rare high-temperature optical elements, whichotherwise could be needed in order to withstand the relatively hightemperatures encountered in a turbine engine environment. Moreover, sucha cooling arrangement is expected to eliminate relatively largetemperature fluctuations in the probe, which otherwise could produceoptical aberrations, (e.g., focal point fluctuations) such as due tophysical shifting of the optical elements and/or warping of structurestherein. Although tube sections 34, 36 need not be attached to oneanother by way of hinges, tube sections 34, 36 may be conceptuallyanalogized to a clam-shell structure for containing and effecting fastand uncomplicated retrieval (when needed) of any of the various opticalelements contained in the interior of inner tube 30.

A means for removably affixing inner tube sections 34, 36 to one anothermay include one or more affixing elements. As illustrated in FIG. 4,non-limiting examples of affixing elements may include straps 48 (e.g.,nickel-chromium alloy straps), tack-welds 50, threaded affixing elements52 (e.g., screws, bolts and nuts), which for example may be insertedthrough respective openings 53 on corresponding alignment tabs, and acombination of two or more of such affixing elements.

FIG. 4 further illustrates a light-redirecting element 54, which may bedisposed at a distal end 56 of inner tube 30. In one non-limitingembodiment, light-redirecting element 54 may be a prism (e.g., atriangular prism), which may be supported at distal end 56 by anaffixing structure 57 not attached to an optically-working surface 58 oflight-redirecting element 54 (e.g., a back end of the prism). In onenon-limiting example, affixing structure 57 may comprise one or moreprotrusions 60 from inner tube sections 34, 36 having a support surface63 (FIG. 5) attached to a corresponding non-optically working surface ofthe light-redirecting element, such as lateral surfaces 62 (FIG. 4) oflight-redirecting element 54. A layer 64 (FIG. 5) of adhesive may bedisposed between support surface 63 and the corresponding surface oflight-redirecting element 54 to establish a joining bond between suchsurfaces.

In one non-limiting embodiment, protrusions 60 may be integrallyconstructed (e.g., machined) at the respective distal ends of inner tubesections 34, 36 of inner tube 30. It will be appreciated that affixingstructure 57 need not be integrally constructed with inner tube sections34, 36 since, as will be now appreciated by one skilled in the art,affixing structure 57 in one alternative embodiment may be a separatestructure, which is mountable onto the respective distal ends of innertube sections 34, 36. It will be appreciated that alternative modalitiesfor light-redirecting element 54 may include one or more reflectingsurfaces (e.g., mirrors) arranged to redirect light.

An optical probe having separable inner tube sections configured tohouse at least one optical element, as disclosed above in the context ofFIGS. 1-5, may be used to practice one or more methods, which in onenon-limiting embodiment may be described below referring to the flowchart shown in FIG. 6.

Subsequent to a start step 98, step 100 allows constructing inner tube30 (FIG. 3) to have at least two corresponding inner tube sections 34,36 separable from one another along longitudinal axis 38 of the innertube 30. While inner tube sections 34, 36 are detached from one another,step 102 allows disposing into either of inner tube sections 34, 36 atleast one optical element, e.g., optical lenses 40, optical spacers 42,as shown in FIG. 3. As will be now appreciated by one skilled in theart, inner tube sections 34, 36 may be fully or partially separable(e.g., by way of hinge elements) from one another. Accordingly, theinner tube sections need not be fully detached from one another sincepartial separation of inner tube sections 34, 36 (e.g., analogous to anopen clam shell) would provide practically unimpeded access to theirrespective interiors to install and/or or retrieve optical elementstherein.

Step 104 allows attaching to one another corresponding inner tubesections 34, 36 by way of at least one removable affixing element, whichwithout limitation may include as shown in FIG. 4, straps 48, weld tacks50, threaded affixing elements 52. Inner tube 30 may then be assembled(step 106) with other components of optical probe 10, such as insertedinto probe tip 28 and outer tubing 22, connected to fitting 20, etc.,(see FIG. 2). Prior to a return step 110, optical probe 10 may then beinstalled (step 108) in viewing port 15 (FIG. 1) of turbine engine 14 tomonitor at least one component (12) of the turbine engine. As may beappreciated in FIG. 1, at least a portion of optical probe 10 may belocated in the hot-temperature environment of turbine engine 14.

In one-limiting embodiment and referring to the flow chart shown in FIG.7, in the event a servicing action (step 114) for optical probe 10 maybe needed subsequent to a start step 112, optical probe 10 may beremoved from viewing port 15 (FIG. 1) of turbine engine 14, and innertube sections 34, 36 (FIG. 4) may be detached (step 116) from oneanother by removing the one or more affixing elements. This allowsretrieving (step 118) the at least one optical element e.g., opticallenses 40, optical spacers 42, as shown in FIG. 3 from either of theinner tube sections to determine a servicing action to perform nextregarding any such optical elements.

In one non-limiting embodiment, a servicing action may comprisereplacing or repairing any such optical elements. Step 120 allowsdisposing into either of the inner tube sections 34, 36 at least oneoptical element which has been repaired or which constitutes areplacement for any retrieved optical element. Step 122 allowsre-attaching to one another the two corresponding inner tube sections34, 36 by way of at least one removable affixing element. Step 124allows assembling the inner tube with the re-attached inner tubesections into the optical probe. Prior to a return step 128, step 126allows re-installing optical probe 30 into viewing port 15 of turbineengine 14 to resume monitoring of the one or more components of theturbine engine.

The present inventors have further recognized that partitioning (e.g.,cutting) a physical structure generally involves certain tangible lossof material. In the case of conventional symmetrical bifurcating of atube (e.g., cutting intended to divide the tube into two equal sizeportions along the longitudinal axis of the tube), the loss of materialcan lead to geometrical distortions and/or fitting incompatibilitiesbetween the tubing sections resulting from such symmetrical bifurcating.Accordingly, the present inventors propose innovative asymmetricalbifurcating of two different tubing structures, which solves in anelegant and cost-effective manner the foregoing issues, and, forexample, may be effective to snugly accommodate cylindrical-shapedoptical elements in the interior of the tubing structures.

In one-limiting embodiment and referring to the flow chart shown in FIG.8 (and the respective isometric views shown in FIG. 9), subsequent to astart step 130, step 132 allows constructing the two inner tube sections34, 36 (FIG. 3) from two different tubing structures, such as tubingstructures 150 and 152, as shown in FIG. 9. In one non-limitingembodiment, a constructing of a first the two inner tube sections maycomprise asymmetrically bifurcating (step 134) along its longitudinalaxis 151 one of the two different tubing structures (e.g., tubingstructure 150 in FIG. 9) to divide into respective first and secondtubing sections 154, 156. The asymmetrical bifurcating is arranged sothat one of the first and second tubing sections (e.g., tubing section154, labeled C1) is sized to compensate for loss of tubing material(conceptually represented by strip 158) due to the bifurcating of tubingstructure 150. Asymmetrical bifurcating may be conceptualized aspartitioning no longer intended to divide the tube into two equal sizeportions.

A constructing of a second of the two inner tube sections 34, 36 maycomprise asymmetrically bifurcating along its longitudinal axis(represented by arrow 153) the other (e.g., tubing section 152) of thetwo different tubing structures to divide into respective tubingsections 160, 162. The asymmetrical bifurcating is selected so that oneof the first and second tubing sections (e.g., tubing section 162,labeled C2) is configured to compensate for loss of tubing material(conceptually represented by strip 164) due to the bifurcating of tubingstructure 152. Prior to a return step 140, step 138 allows grouping therespective tubing sections which are compensated for loss of tubingmaterial (e.g., tubing sections labeled C1 and C2). The grouped tubingsections labeled C1 and C2 constitute the two inner tube sections 34, 36for inner tube 30. In one non-limiting embodiment, the tubing sections154 and 160, which are not compensated for loss of tubing material maybe discarded.

While various embodiments of the present invention have been shown anddescribed herein, it will be apparent that such embodiments are providedby way of example only. Numerous variations, changes and substitutionsmay be made without departing from the invention herein. Accordingly, itis intended that the invention be limited only by the spirit and scopeof the appended claims.

1. An optical probe comprising: at least one optical element; and aninner tube housing the at least one optical element, wherein the innertube comprises at least two cooperating inner tube sections separablefrom one another along a longitudinal axis of the inner tube.
 2. Theoptical probe of claim 1, further comprising means for removablyaffixing the at least two corresponding inner tube sections to oneanother.
 3. The optical probe of claim 1, further comprising at leastone affixing element to removably affix the at least two cooperatinginner tube sections to one another, wherein the at least one affixingelement is selected from the group consisting of a strap, a tack-weld,and a threaded affixing element.
 4. The optical probe of claim 1,wherein the at least two cooperating inner tube sections of the innertube define a hollowed interior having a varying diameter along thelongitudinal axis.
 5. The optical probe of claim 1, wherein the at leastone optical element comprises a series of optical lenses stacked alongthe longitudinal axis of the inner tube.
 6. The optical probe of claim5, further comprising at least one optical spacer interposed between atleast a pair of the optical lenses.
 7. The optical probe of claim 1,wherein the inner tube comprises a stop formed on an outer surfacethereof.
 8. The optical probe of claim 1, wherein the inner tubecomprises at least one alignment tab formed on an outer surface thereof.9. The optical probe of claim 1, further comprising a light-redirectingelement disposed at a distal end of the inner tube, wherein thelight-redirecting element is supported at said distal end by an affixingstructure not attached to an optically-working surface of thelight-redirecting element.
 10. The optical probe of claim 9, wherein theaffixing structure comprises at least one protrusion from the inner tubesections having a support surface attached to a non-optically workingsurface of the light-redirecting element.
 11. The optical probe of claim10, wherein the at least one protrusion is integrally constructed at thedistal end of the inner tube.
 12. The optical probe of claim 10, furthercomprising adhesive between the support surface and the non-opticallyworking surface of the light-redirecting element.
 13. The optical probeof claim 9, wherein the light-redirecting element is selected from thegroup consisting of a prism and a mirror.
 14. The optical probe of claim9, wherein the light-redirecting element comprises a prism, and furtherwherein the affixing structure comprises respective protrusions from theinner tube sections, each protrusion having a support surface attachedto a corresponding lateral surface of the prism.
 15. The optical probeof claim 14, further comprising adhesive disposed between the supportsurfaces and the lateral surfaces of the prism.
 16. The optical probe ofclaim 1, further comprising an outer tube housing the inner tube.